A cellular communications system typically has base stations (BSs) distributed throughout an area to provide data connectivity with mobile stations (MSs) throughout the area. The cellular system allows wireless communications to use less power and it allows frequencies to be reused by different subscribers connected to different base stations. Each base station connects through a communications infrastructure to a communications backbone to connect to other subscribers and to users and systems outside the cellular system. Because frequencies and channels are reused by different BSs, when a MS is near the edge of a cell, signals for other MSs in other cells can interfere with the MS's signal.
In mobile broadband radio systems such as IEEE 802.16m or 3GPP LTE (Third Generation Partnership Project Long Term Evolution) systems, Fractional Frequency Reuse (FFR) is used to mitigate the interference levels that users on the edge of a cell receive from users in other nearby cells. FFR effectively alleviates the interference levels on some subcarriers by setting these subcarriers' transmitting power among neighbor BSs in a certain pattern. A framework that allows the adaptation of an FFR configuration to achieve an optimal system level power loading, spectrum partition and resource allocation is referred to as Adaptive Fractional Frequency Reuse (AFR). Unlike traditional FFR which allocates an MS to a specific frequency partition according to the MS's geometry semi-statically, AFR also takes into account the short term fading of different frequency partitions to achieve even better system performance.
To support AFR, the BS needs to broadcast a resource metric for each frequency partition that it serves once in every broadcast period or once in some number of superframes. Each resource metric is 16 bits plus an identification of the particular frequency. This information is used by the MS to choose a frequency partition for its own use. After receiving the frequency partition, data, the MS sends a message to the BS to inform it as to which frequency partition it has selected. The signaling required to support AFR adds significant additional data to the broadcast signaling. In addition, the MS can report interference statistics that is measures for each partition back to the base station. With many MSs all reporting statistics back to the BS, significant signaling resources can also be required.